Have you ever looked at a Heinz ketchup bottle and thought, "Huh, what does that 57 mean?"

Well, it means nothing. Or almost nothing.

That's according to Emily Ruby, the curator of the Heinz exhibit at the Senator John Heinz History Center in Pittsburgh. Sen. Heinz was the great-grandson of the founder of the HJ Heinz company, Henry John Heinz.

In a recent interview with Business Insider's podcast, "Household Name," Ruby said that legend has it a young Henry John Heinz was riding a train in New York City around the year 1896 when he saw an advertisement for "21 varieties of shoes." He was looking for new ways to market his food business, and he liked the idea of pegging a number to his product.

He landed on the number 57 — even though his company had more than 60 products at the time.

There are a lot of theories for why he chose that number. Some say five was his lucky number and seven was his wife's favorite number. Some speculate on the religious connotations behind the number seven, while others think he just liked the way 57 looked or sounded.

Ruby said she's heard a lot of different ideas.

"I had a guy come up to me at a talk and say that he knew, because his grandfather was friends with Heinz, that it was because the streets in Pittsburgh at the time ended at 56 going up the river, the Allegheny River where he lived, so there's all kinds of theories out there," she said.

Brian Butko, the Heinz History Center's director of publications, who also wrote an article about the 57 varieties, said that the mystique of the label has become more important than its actual meaning.

"The sound and look of it meant more to him than the actual number," Butko said. "And that's the difference between a company that thinks they're bragging by saying, 'Oh we have 157 [varieties],' and an innovator who sees the value in the sound and look of something easily graspable."

Even though the 57 was largely a made-up number, the Heinz company assigned 57 products to a list of the varieties, according to an ad from 1924. Classic Heinz tomato ketchup was listed at No. 48 on the list, with prepared mustard right behind it at 49. No. 1 on the list was baked beans with pork and tomato sauce, while No. 57 was tarragon vinegar.

Other products on the list included varieties of preserves, jellies, pickles, gherkins, vinegars, soups, and pastas. The ad shows that the products originated in various countries around the world. Most of the products are still more popular abroad than in the United States.

Paul Sakuma / AP Images
"In the [Heinz History Center] exhibit, some of the most popular products are the ones that we don't have here in the United States but are sold in Europe," Butko said.

Another popular product at the exhibit is horseradish, which was the first product Heinz ever made from his family's land in Sharpsburg, Pennsylvania. He was eight years old when he thought of an innovative way to market his product: putting it in a clear jar so that customers could see that he had the whitest and purest roots in his horseradish.

His first food company declared bankruptcy in 1875, but his nearly identical HJ Heinz company became successful just a few years later. His marketing strategy took off after he came up with the idea for his "57 varieties" slogan in the 1890s, even as the number of products the company offered stretched into the hundreds and thousands.

"[The slogan] wasn't just on the products, it was all on the advertising, on the bottling, and his salesmen would use that pitch, too," Ruby said.

To promote his 57 varieties, Heinz installed the first-ever electric sign on the site where the Flatiron Building now stands in New York. It was a 43-foot, six-story tall image of a pickle with "57 varieties" written underneath. He put ads with a large 57 all over the place, including on an Atlantic City pier. He also put massive cement 57s on hillsides close to railroad lines so that passengers would see them during their trip.

All of that effective advertising and branding led the 57 varieties to become ingrained in culture, and they have come to be a nickname for many different things. For example, a bingo caller might say "57 varieties" when they pull out the "57" bingo ball, "57 varieties" in draw poker is when 5 and 7 are wild cards, and a mutt might be called "57 varieties" or "Heinz dogs."

The slogan has also appeared in popular culture, like in Jimmy Buffett's song "Cheeseburgers in Paradise," and both the novel and film "The Manchurian Candidate."

It also helps that the campaign was launched before there was an onslaught of advertising everywhere you turned.

"Now, we all run screaming from advertising that's everything from the floor of a supermarket to the ice of a hockey rink, electronic billboards," Butko said.

"But at the time, his advertising was innovative, so even if it was everywhere, it never pushed the point where people had too much of it. And then it's carried on into our modern, post-modern world, where things like that, they grow beyond their original meaning."